1. Field of the Invention
This invention relates generally to the field of distributed multimedia streaming and more particularly to distribution of live TV multicast programming using multicast and unicast methods with automatic switching to enable multiple speed trick mode functions.
2. Related Art
Broadcast of live TV programming is desirable for TV-over-IP applications. Many networks are enabled for muticast transmission to support direct streaming of the live broadcast. The most efficient approach to serve many viewers watching the same content is to stream via multicast, utilizing the built in capabilities of the network to serve many clients. However, the key new features of IPTV over traditional broadcast mode of TV viewing is the support for time shifted content and multiple speed trick mode (fast forward and rewind) which can be achieved only with unicast streams. At any given time, the contents viewed by most viewers are live TV broadcast for which multicast streaming is employed. However, viewers selecting trick mode functions desire to do so without requirements for switching system inputs or additional command selections.
Consequently, it is desirable to support multicast IP traffic while providing automatic switching to unicast streaming to enable trick modes and time shift content viewing only to the viewers employing the trick mode commands. It is further desirable that transition between multicast and unicast modes be seamless and provide the greatest efficiency in streaming mode for the overall system.